Configuring the high-resolution timer

You can configure agent computers to use a high-resolution timer when collecting performance data. The high-resolution timer ensures that all measurements are precise to within 1 millisecond.

Before you begin

The high-resolution timer is used by default on the Linux operating system. You do not need to configure the high-resolution timer on the Linux operating system. For the Microsoft Windows, AIX®, and z/OS® operating systems, the high-resolution timer is not used by default.

Enabling the high-resolution timer can increase processor usage on Windows agent computers. Typically, processor usage increases by 10% to 25%, but the increase can vary based on workload. Enable the high-resolution timer on Windows agent computers if you are measuring response times less than 15 milliseconds. Enable the high-resolution timer if you are measuring response times of less than 150 milliseconds and need 1 millisecond precision instead of 15 millisecond precision. If you enable the high-resolution timer on Windows agent computers, monitor the processor usage to determine whether the trade-off of higher processor usage is acceptable.

Procedure

To enable the high-resolution timer on an agent computer:

  1. In the Test Navigator, open the location that represents the agent computer.
  2. Click the General Properties tab.
  3. On the General Properties page, click Add to create a property for the selected location.
  4. In the New Property window, create a property entry:
    1. In Property Name, type RPT_VMARGS.
    2. In Operator, select =.
    3. In Property Value, type -DrptNanoTime.
    If you need to set multiple RPT_VMARGS values for a location, place them in the same property entry and separate them with a space. Do not use multiple property entries to set multiple RPT_VMARGS values for a location.
  5. Click OK, and then save the location. The high-resolution timer is enabled for the location.
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